Question

Number of circles that can be drawn touching all the three lines $x+y-1=0,x-y-1=0$ and $y+1=0$ , is

• A. $0$
• B. $2$
• C. $3$
• D. $4$

Answer 1

Answer: (D)

$4$

Plotting the given lines, we observe that they form a right angled triangle.

Every triangle have $1$ incircle and $3$ excircle.

$\therefore$ Number of circles that can be drawn touching all the three lines $x+y-1=0,x-y-1=0$ and $y+1=0$ is $4$

Hence, option D.